Neurodegenerative disorders affect many people worldwide. These disorders include peripheral neuropathies, which are a group of neurodegenerative disorders affecting the peripheral nerves, such as peripheral neuropathy caused by chemotherapy or diabetes; disorders of the central nervous system, such as Alzheimer's disease and Parkinson's disease; and motor neuron diseases, such as amyotrophic lateral sclerosis (ALS). Currently, no effective therapy for preventing nerve degeneration exists, except in cases of autoimmune peripheral neuropathies.
Heat shock proteins are a class of functionally related proteins involved in the folding and unfolding of other proteins. They play an important role in the cell under normal conditions and also are a primary part of the heat shock response. They make up approximately 1% to 2% of total protein in unstressed cells. This percentage increases to 4% to 6% of total protein in cells that are stressed, such as during elevated temperatures, inflammation, or infection.
Heat shock proteins have several important functions in a cell under normal conditions. One function is to act as intracellular chaperones for other proteins. By helping to stabilize partially unfolded proteins, heat shock proteins aid in transporting proteins across membranes within a cell. They also play an important role in other protein-protein interactions, such as protein folding, assisting in the establishment of proper protein conformation, preventing unwanted protein aggregation, and carrying old proteins destined for degradation to a proteasome in the cell.
Heat shock proteins, however, also can assist in promoting diseases or disorders. For example, heat shock proteins can aid in the correct functioning of tumor promoting proteins, such as oncoproteins, and they have been found to be overexpressed in a range of cancers. They also may contribute to tumor cell survival by stabilizing aberrant signaling proteins and by interfering with apoptosis.